Coded track circuit for railways



2 Sheeis-Sheet l INVENTOR Feb. 10, 1942. M. HORMATS I CODED TRACK CIRCUIT FOR RAILWAYS Filed Dec. 29, 1939 ATTORNEY 2 Sheets-Sheet 2 INVENTOR T) "E U MM ATTORNEY Feb. 10, 1M2. M. HORMATS CODED TRACK CIRCUIT FOR RAILWAYS Filed Dec. 29, 1939 Patented Feb. 10, 1942 UNETED STATES A'lN'l CFFICE.

CODED TRACK CIRCUIT FOR RAILWAYS Myer Hormats, Rochester, N. Y., assignor to General Railway Signal Company, Rochester, N. Y;

This invention relates in general to coded track circuits for railways, and has more particular reference to a circuit including approach control without the use of line wires.

In the wayside signal systems employed in ence characters, with distinctive exponents, in

accordance with the particular location.

connection with railway operation the spacing between signals varies widely in accordance with the topography and local conditions, but in general the distance is as great as possible, consistent with good practice, in order to economize on apparatus employed at the signal locations. If the spacing of signals be great enough, the cost of line wire for various purposes such as approach control, may become practically prohibitive and hence, large economies may be efv fected by eliminating the need for such line wire, even though additional apparatus over the usual, be employed at the signal locations.

In many cases, local conditions, dueto weather and to the presence of corrosive substances, may limit the life of line wires to very short periods such as one or two years, and hence, the elimination of line wires is an economy under such conditions even though the signals be relatively closely spaced.

With the above and other considerations in mind, it is proposed, in accordance with the present invention, to provide means, in conjunction with a coded trackway signal system, whereby supplemental control, such as, approach control without the use of any line wire, for the energization of wayside signals, for example, is made possible.

Further objects, purposes and characteristic features of the present invention will appear as 'l the description progresses, reference being made tothe accompanying drawings showing, in a wholly diagrammatic manner, and in no way whatsoever in a limiting sense, one form which the invention can assume. In the "drawings:

The drawings, comprised of Fig. 1A and Fig. 1B, are a wholly schematic showing of a railway track layout including one form of the present invention.

Referring now to the drawings, there is shown sulating joints 2, with signals S, located along;

the trackway for governing trafiic moving from West to east, as indicated by the arrows 3.

Since the arrangement of parts at each of the signal locations is identical, like parts at the various locations will be identified by like refer- Consider, for example, the apparatus employed at the location of signal S At the entrance end of block B is a code following track relay CFT connected across the track rails in series with a variable resistance '4 and a back contact 5 of an impulsing relay IMP whereby the code following track relay is connected to respond to code in the track rails, when the impulsing relay is in its'retracted position. Connected across the track rails in multiple with the code following track relay is an inverse code or impulsing battery 6 which latter is in series with a front point of the impulsing relay, whereby the inverse code battery 6 is connected across the entrance end of track section B, when the impulsing relay IMP is in attracted position.

The signals employed to exemplify this invention are of the color light type and each includes three difierent aspects, r g and g respectively red, yellow and green, and indicate danger, caution and clear. The wayside signals can, of course, be of any other type, as, for example, a usual semaphore signal, or the like. However, the type of signal shown in the drawings, serves for the purpose of illustration, and can be of the construction and operation as disclosed in Patent No. 2,125,257, granted July 26, 1938, to O. S. Field.

At each signal location is a code following track repeater relay CFTP and this relay includes an operating winding 1 and an inductive winding 8 which windings are physically separate,

' but are inductively related to each other, whereby any change in current flow in winding 1 produces an induced voltage in winding 8 The code following track repeater relay is energized through an obvious circuit, which includes contact finger 9 and front point of track relay CFT Connected across contact finger 9 and its back point is a resistance and condenser unit I0 which is employed for are suppression, and reduction of radio interference.

The inductive winding 8 of the code track repeater relay is connected to the winding of an impulsing relay IMP and has in series therewith a rectifier H of the half wave type, and

so poled that it blocks the flow of currentv produced by voltage induced in the winding 8 when the flux in the winding 7 increases. In other words, when code following track repeater relay CF'IP is energized, flux builds up in winding 1 and induces a voltage in winding 8 which tends to send a current against the blocking effect of the rectifier H and hence, when this repeater relay picks up the impulsing relay is not energized.

Upon the code following repeater relay being deenergized, the flux in winding 1 collapses and induces a voltage in the winding 8 to send a current flowing in the direction indicated by arrow I2 whereby to energize the impulsing relay and cause it to move its contact finger 5 to the right.

Impulsing relay IMP is a polar relay of any usual or desired type and regardless of the presence of rectifier I I responds only to current flowing in the direction of arrow I2 to move its contact finger to the right. Upon the impulsing relay being deenergized (or being energized by current of abnormal polarity), contact finger 5 moves to the vertical, pendant, position, as shown, and hence, the impulsing relay is in its retracted position when deenergized, which includes the time while any attempt is made to energize it in the direction the reverse of that of the arrow I2 Not only such current flow is blocked by rectifier H but if the rectifier were to break down com pletely, the impulsing relay would not respond to such current fiow, but would move its contact finger to the pendant deenergized position, as shown. In effect, current of a polarity opposite to that of the arrow I2 if not blocked by rectifier H would merely drive the contact fingers to their deenergized positions beyond which they are prevented from moving, by any suitable stop means, such as the back contact point shown in connection with contact finger 5 The code following track repeater relay has a contact finger I3 which energizes first one part, and then the other, of the primary winding p of a transformer T in first one direction, and then the other, in the usual pushpull transformer operation such, for example, as shown in Patent No. 1,794,609, granted March 3, 1931, to W. D. Hailes. A condenser M is connected across the contact points of finger I3 for the purpose of arc suppression.

The. secondary winding s of transformer T is connected to the primary winding 65 of a transformer t the secondary winding Ilia of which is connected to the input side of a full wave rectifier H3 the output side of which is connected to the winding of the distant signal control relay D The signal relay D is of any usual direct current type, and is slow to release because of the rectifier connected across its windings.

A home signal control relay H which is of any usual direct current type, has connected across its winding a half wave rectifier il poled in the direction to furnish a low resistance path for the current produced by the voltage of self -induction when the relay is deenergized, thus making the relay slow to release. This relay H is connected across a portion of the secondary winding of transformer T and in series with a contact finger 48 on the code following repeater relay, with the front and back points coacting with this contact finger Hi connected to the transformer secondary winding s on opposite sides of the connection of the relay H to the secondary by the wire l3 This furnishes a mechanical fullwave rectifier for relay H whereby to supply the relay 0, with pulsating direct current. The mechanical rectifier is employed in preference to a static rectifier, such as H3 in order to guard against faulty operation in the event the local direct current supply to the primary winding p of transformer T is from a storage battery on trickle charge. If a static rectifier were employed, and the code following track repeater relay should not oscillate its contact finger [3 the pulsating direct current from the storage battery charging circuit which is connected, of course, in multiple with the storage battery, across the primary winding, would still cause a transfer of energy from the primary to the secondary of the transformer T and pick up relay H even though, as will be apparent from the following description, relay H should then be in released position.

Employed in this system is a coding means, which can take any usual or desired form, but which, for the purpose of illustration, is shown as involving a code motor 0M which is always energized, through an obvious circuit and which operates fingers I and 15 respectively, at their indicated rates, to close and open on their front points, times per minute, and '75 times per minute. This can be accomplished by connecting the motor shaft to cams having various numbers of dwells thereon, which move the contact fingers, or by various gearing, or, if desired, by a separate, constant speed motor for each code rate, or other arrangements. Associated with the code motor CM is a code following repeater relay CFP which receives energy through contact finger 20 and either its front or back point, depending upon whether relay H is attracted or retracted. When the energy fiows through the front point it is controlled by the code fiinger I80 and when through the back point, by the contact finger 15 whereby to cause the code following repeater relay to pick up and release either 180 times, or 75 times, per minute.

The code following repeater relay CFP operates a contact finger 21 to connect an impulsing battery 22 in series with a variable resistance 23, across the exit end of the track rails of block A, by means of wires 24 and 25 when the code following relay is in its attracted position. When the code following repeater relay is in its retracted position, it connects a code following approach relay CFAR across the exit end of the block A, by means of the same wires 24 and 25 The code following approach relay controls an approach repeater relay ARP through a circuit including contact finger 2G and front point of the code following approach relay. The approach repeater relay ARP has a rectifier 21 connected across its windings, poled in a direction to make the relay slow to release.

The signal circuits are controlled by the relays H and D and are all supplied with energy through contact finger 2B and back point of the approach repeater relay AR-P It is clear from the drawings that the signal is prepared to display a green light when relays H and D are both in attracted position, to display a yellow light when relay H is attracted, and. relay D is retracted, and to display a red light when the relay H is retracted. The signal, however, is not energized unless the approach repeating relay ARP is deenergized and this occurs, as will appear as the description progresses, only when the immediately preceding track section is occupied. 7

The further description of the system can best be understood by explaining the operation of the system when a vehicle is occupying the track.

As shown in the drawings, the vehicle represented by the wheels and axle V, is occupying block D. The code which is applied to the rails at the exit end of this block 'D is shunted away from the track relay at the entrance end of this block, whereby relay CFT assumes, and remains in, retracted position, to thereby prevent any transfer of energy from the primary to the sec- 'ondary of the transformer T and thus to cause both of the signal control relays H and D to assume their retracted positions, whereby to prepare the signal S to display a red indication.

With the relay H in retracted position the code following repeating relay CF P is operated at the '75 rate, to thereby place '75 rate code to the eXit end of block 0.

The code following track relay CFT thus perates at the 75 rate, to transfer energy to the secondary of transformer T and thus energize relay H Relay D is not energized, however, since its circuit is tuned by means of condenser 30 so as not to respond to the 75 rate code, but only to respond to the 180 rate code. Accordingly, signal S is prepared to display the yellow indication. I

In like manner, code motor CM with relay H attracted, places code on the exit end of block B at the 180 rate, whereby to cause relays H and D to be in attracted position, and thus prepare signal S to display a green light.

The block A has 180 rate code applied to its exit end, etc., for all preceding blocks, providing there is no occupancy.

It is seen that with this system, the signal at the entrance end to an occupied block is prepared to show a danger or stop indication, the one next to the rear of the occupied block, a caution indication, and the one next to the rear thereof, or all blocks to the rear thereof, a proceed or clear indication.

With the approach control, however, which is involved in this system, all signals are normally dark, and are energized only upon the block next to the rear thereof being occupied.

Consider, for the moment, signal S which is prepared to display a yellow indication, but which is deenergized because the approach repeater relay ARP is energized. Upon a vehicle entering block B, track relay CFT releases and remains in retracted position, whereby the impulsing relay IMP after momentarily picking up on the release of its track relay, releases its armature and remains in retracted position, whereby to disconnect impulsing battery 6 from the entrance end of block B, and thus to remove energy from the inverse code following approach relay CFAR As a result, approach repeater relay ARP releases, to place energy on the signal circuit, and cause the display of a yellow signal.

Thus, as a train proceeds along the track, the signal it is approaching is energizedautomati cally and remains energized until the train has passed off of one track section and onto the next, whereby to energize the next signal in advance thereof.

Also, it can be seen that coded energy is placed on the exit end of each block in accordance with traffic conditions ahead, in the form of separate current impulses, spaced by periods when no current is present, and during these so-called 0 periods of code the impulsing relay, as IMP is energized to place coded inverse control energy on the entrance end of its block, whereby to maintain the inverse code repeater relays energized and hence to maintain its signal deenergized. By this means, economy in the operation of the signals is realized.

It can be appreciated that the approach control is dependent upon the impulsing relays fol lowing the off periods of code, and if these impulsing relays be not fast enough to respond, the approach control fails.

With a relatively fast code, such as per minute, in each second there is, on the average, three current impulses, and three blank portions, and if these current impulses and blank or off portions be equal in duration the off periods each persist for but of a second, or .166 second. During this short period of time of off period, the track relay must release, the flux in the code following repeater relay must decay, and the induced voltage in the winding 8 of this relay must send a current through the impulsing relay to cause the impulsing relay to pick up, and then the impulsing relay must remain up long enough to place an approach control pulse of current on the track rails from the impulsing battery 6. By providing a specially constructed relay for the code following track repeater relay, such as CFTP in which there is an inductive winding included, the effect of a blank period of code on the impulsing relay is earlier felt during the blank period than if the transformer T were employed to operate the impulsing relay. It is by virtue of this early effect of the blank period of code on the impulsing relay, that it can operate satisfactorily and follow a relatively fast code. Such would not be the case if the impulsing relay were operated from the transformer T.

A further reason for the impulsing relay being sufficiently quick acting to operate in connection even with the relatively fast codes, such as the 180 rate per minute, is by virtue of the half-wave rectifier llconnected in series with the operating winding of the impulsing relay IMP This rectifier is connected as described above, that is, so as to permit the operative half cycle of alterhating current to flow, but to suppress the inoperative half cycle of current. In other words, with the rectifier H so poled as to facilitate current due to what may be called the operative polarity, and to block the flow of current due to what may be called the inoperative polarity, the impulsing relay responds more quickly to energizing current than would otherwise be the case. Hence, even with a relatively fast code, and hence a relatively short blank or off period, there is still time enough for the impulsing relay to up and apply the inverse control current from battery E to the track rails.

One theory of operation of this combination of polar relay and rectifier is that, without the rectifier, the inoperative polarity of current sets up a flux condition in the core of the impulsing relay which must be destroyed by the operative polarity of current before the operative current can start building flux in the direction to move the armature to attracted position. With the inoperative current suppressed, this antagonistic flux is not produced, and hence the time for destroying it is saved, and as a result the imi'lulsing relay readily and reliably. follows the faster codes.

The system has been shown in the drawings as empioying coded direct current for signal control and. coded direct inverse current for approach lighting control. It is obvious, however, that if alternating current should be available along the trackway, as by means of a power line or any other manner, it would be entirely feasible to employ the alternating current instead of direct current. All that would be necessary, in order to change the system over to an alternating current one, would be to replace the battery sources G and 22, with alternating current sources of energy, and to replace the track relays CFT and the code following approach relay CFAR, which are now of the direct current type, with alternating current relays. The track relay would of course be of the polar type and this, presumably, with alternating current, would require a two element relay with a local winding and a control winding.

The above rather specific description of two forms which the invention can assume is given solely by way of example, and is not intended in any sense whatsoever, to be limiting in nature. It is obvious that various modifications and adaptations may present themselves from time to time, and it is contemplated and intended that the present application shall cover all such variations in parts and arrangements of parts, except insofar as they are specifically excluded by the appended claims.

Having described my invention, I now claim:

1. In a coded control system for railways, in combination, an isolated first signal block, an isolated second signal block in advance of said first block, a plural aspect wayside signal at the entrance end of the second block, means for applying coded signal control current, comprised by alternate on and 011 periods of current, to the exit end of the first block and in accordance with traffic conditions in advance, a source of approach control energy at the entrance end of said first block, a track relay at the entrance end of the first block responsive to the code, a track repeater relay having a control winding and a winding inductively related thereto, a polar relay connected across the inductive winding and so poled as to assume its energized position only in response to current induced in the inductive winding due to the control winding becoming deenergized, circuit means effective when the polar relay is in its energized position for placing approach signal control energy on the entrance end of the first block, and means at the exit end of the first block and responsive to the approach energy to maintain the signal at the entrance end of the second block deenergized.

2. In a coded control system for railways, in combination, two successive but isolated signal blocks, a plural aspect wayside signal at the entrance end of the advance block, means for applying coded signal control current, comprised by alternate on and ofi periods of current, to the exit end of the rear block and in accordance with trafiic conditions in advance, a track relay at the entrance end of the rear block responsive to the code, a track repeater relay having a control winding and a winding inductively related thereto, a polar relay energized from the inductive winding and so poled as to assume its energized position only in response to current induced in the inductive winding due to the control winding becoming deenergized, a source of approach control energy at the signal location of the rear block, circuit means effective only when the polar relay is in its energized position for placing approach signal control energy on the entrance end of the rear block, and means at the exit end of the rear block, and responsive only to the approach control energy. to maintain the signal for the advance block deenergized.

3. In a coded control system for railways, in combination, two successive isolated signal blocks, a plural aspect wayside signal at the entrance end of each of said blocks, means for applying coded signal control current, comprised by alternate on and off periods of current, to the exit end of the first block and in accordance with trailic conditions in advance, a track relay at the entrance end of the first block responsive to the code, a track repeater relay for controlling the signal at the entrance to such first block and having a control winding and a winding inductively related thereto, a polar relay energized from the inductive winding and so poled as to assume its energized position only in response to current induced in the inductive winding due to the control winding becoming deenergized, a half-wave rectifier in series with the polar relay and so poled as to block current flow due to the said control winding becoming energized, a source of approach control energy at the entrance end of the first block, circuit means effective when the polar relay is in its energized position for placing approach signal control energy on the entrance end of the first block, and means at the exit end of the first block, and responsive to the approach energy, to maintain the signal at the entrance end of the second block deenergized.

4. In a coded control system for railways, in combination, an isolated signal block, a plural aspect wayside signal at the exit end of the block for governing traffic into the track section in advance of such block, means for applying coded signal control current, comprised by alternate on and off periods of current, to the exit end of the block and in accordance with traflic conditions in advance, a track relay at the entrance end of the block responsive to the code, a track repeater relay controlled by said track relay and having a control winding and a winding inductively related thereto, a polar relay connected across the inductive winding and so poled as to assume its energized position only in response to current induced in the inductive winding due to the control winding becoming deenergized, a half-wave rectifier in series with the polar relay and so poled as to block current flow due to the said control winding becoming energized, a source of approach control energy at the entrance end of said block, circuit means effective only when the polar relay is in its energized position for placing approach signal control energy on the entrance end of the block, and means at the exit end of the block, and responsive only to the approach energy, to maintain said signal deenergized.

5. In a coded wayside signal system for railways, in combination, an isolated block, a plural aspect signal at the entrance end of the block, means at the exit end of the block for applying energy to the exit end of the block. variously coded in accordance with traific conditions ahead, a polarized impulsing relay'at the entrance end of the block, a code following relay at the entrance end of the block, a code following repeater relay at the entrance end of the block and having a control and an inductive winding, an inverse code energy source at the entrance end of the block, means for connecting the inverse code source across the entrance end of the block only when the polar relay is energized, and an energizing circuit for the polar relay including a half-wave rectifier, and energized only by current induced in the inductive winding due only to the control winding becoming deenergized.

6. In a coded wayside signal system for rail- Ways, in combination, an isolated block. a plural aspect signal at the exit end of the block and governing trafiic into the track section in advance of said block, means at the exit end of the block to apply variously coded energy to the exit end of the block in accordance with traffic conditions ahead, a polarized impulsing relay at the entrance end of the block, a code following relay at the entrance end of the block, a code following repeater relay at the entrance end of the block controlled by said code following relay and having control and inductive windings, an approach energy source at the entrance end of the block, means for connecting the approach source across the entrance end of the block only when the polar relay is energized, an energizing circuit for the polar relay including a half-wave rectifier and energized only by current induced in the inductive winding due only to the control winding becoming deenergized, and means at the exit end of the block, and responsive only to said approach energy, to maintain said signal deenergized.

'7. In a coded control system for railways, in combination, an isolated signal block, a plural aspect wayside signal at th exit end of said block for governing traffic into the track section in advance of such block, means for applying coded signal control current consisting of alternate on and oil periods of current to the exit end of the block and in accordance with traffic conditions in advance, a track relay at the entrance end of said block responsive to the code, a track repeater relay controlled by said track relay and having a control winding and a winding inductively related thereto, a polar relay connected across the inductive winding and so poled as to assume its energized position only in response to current induced in the inductive winding due to the control winding becoming deenergized, a source of approach control energy at the entrance end of said block, circuit means effective only when the polar relay is in its energized position for placing approach signal control energy on the entrance end of the block, and means at th exit end of the block and responsive only to the approach energy to maintain said signal deenergized.

8. In a coded control system for railways, the combination with an isolated signal block, a plural aspect wayside signal at each end of said block, means for applying impulses of main track current in accordance with traffic conditions in advance at one end of said block to characterize a code of which the impulses are separated by 01f periods, means including a code following relay at the other end of such block which is picked up in respons to each impulse and is dropped away for each off period of said main track current and having a control winding and an inductive winding inductively related to said control winding, means controlled by said code following relay for controlling the signal at said other end of said block, a source of inverse code energy at said other end of said block, a polar impulsing relay at said other end of said block and energized from the inductive winding of said code following relay and so poled as to assume its energized position only in response to current induced in said inductive winding due to the control winding becoming deenergized, circuit means eifective only if said polar relay is in its energized position for placing inverse code energy across the track rails at said other end of said block, and a relay at the said one end of said block connected across the track rails of said block during the off period of the main code only for controlling th signal at said one end of said block.

9. In a coded control system for railways, the combination with an isolated signal block, a plural aspect wayside signal at each end of said block, means. for applying impulses of main track current in accordance with traific conditions in advance at one end of said block to characterize a code of which the impulses are separated by off periods, a code following relay at the other end of such block which is picked up in response to each impulse and is dropped away for each ofi period of said main track current, two windings inductively related to each other, means including a contact closed when said code following relay is energized for energizing said first Winding each time said code following relay picks up said other winding having a voltage induced therein due to said first winding becoming energized and becoming deenergized, means including said first winding controlled by said code following relay for controlling the signal at said other end of said block, a source of inverse code energy at said other end of said block, a polar impulsing relay at said other end of said block and energized from the other winding of said inductively related winding and so poled as to assume its energized position only in response to current induced in said other winding due to the first winding becoming deenergized, a half-wave rectifier included in series with said polar relay so poled as to block current fiow in the said other winding due to voltage induced therein due to said first winding becoming energized, circuit means effective only if said polar relay is in its energized position for placing inverse code energy across the track rails at said other end of said block, and a relay at the said one end of said block connected across the track rails of said block during the off periods of said main code only for controlling the signal at said one end of said block.

MYER HORMATS. 

